This invention relates to a device for analyzing engine ignition systems. It is particularly adapted to assist repair persons in diagnosing ignition and power faults in small engines such as outboard or marine engines of the spark ignition types either in place or in repair shops. It is presently known to conduct a series of engine analyzing tests on such engines by means of an oscilloscope which when equipped with special auxiliary devices can when connected to both the low and high voltage portions of the spark ignition system of an engine, analyze, compare and even quantify ignition faults of such engines. However oscilloscopes and their auxiliary diagnostic equipment are extremely expensive and the analysis techniques utilized therewith are somewhat complex to learn. However, not withstanding the wide spread availability of such oscilloscope systems, many voltage diagnostic tests can be accomplished without resort to such expensive equipment and accordingly a need and a market exists for such less complex and accordingly less expensive equipment.
Some of such less expensive equipment has been only recently introduced while other examples of such equipment have been available for a long time. Generally such prior art devices include those which test spark efficiency by lighting of a neon or other light and those which singly observe a spark gap jump. The relative spark intensity of several cylinders of an engine however cannot be determined by observing a single spark. Thus it would be advantageous to be able to view the several sparks of multiple cylinder engines simultaneously so that a direct comparison thereof can be made. Many of these devices also do not provide a grounding circuit wherein the availability of spark while the engine is not running can be determined.
Representative of such prior art devices are disclosed in the following U.S. Pat. Nos.: 1,915,709 issued June 27, 1933; 1,948,882 issued Feb. 27, 1934, 2,317,263 issued Apr. 20, 1943; 2,665,408 issued Jan. 5, 1954; 2,841,761 issued July 1, 1958; 3,521,157 issued July 21, 1970; 3,763,421 issued Oct. 2, 1973; 3,806,796 issued Apr. 23, 1974 and 3,828,246 issued Aug. 6, 1974.
Despite the availability of the above devices, a need exists for a single device which can be conveniently operated in a simple and efficient manner for analyzing not only the high voltage output of the ignition system fed to each of the several spark plugs of a multi cylinder engine but further providing for the simultaneous observation of the spark gap of each such electrical circuit. Attributes which can be advantageously incorporated in such a device would be the ability to run the engine in a normal manner while connected thereto, provision for the modification of the spark gap within the device without shutting off the engine, and the ability to selectively shunt out the ignition to any one or multiple numbers of the spark plugs to determine the power loss, if any, of these cylinders as measured by the drop of revolutions per minute of the engine itself.
It is accordingly a primary object of the present invention to provide such an engine analyzer device having the above attributes which can be used in a safe and efficient manner.
This and other objects as will become hereinafter more apparent are accomplished by the provision of an engine analyzing device for testing both ignition and combustion power of engine cylinders comprising a housing including a directly observable and adjustable spark gap having electrical connections on opposite sides thereof and including a ground connection, means for connecting the high tension output of one or more engine cylinders to one side of said gap and the spark plug of said cylinder or cylinders to the other side thereof, and a switch movable to first, second and third positions wherein the first position connects the spark plug side of said gap with said ground whereby high tension voltage is directed through said gap and then to ground, said second position makes no connection between said gap sides and ground whereby high tension voltage is directed through said gap and then to the spark plug of said cylinder and said third position interconnects said opposite sides of said gap whereby high tension voltage by passes said gap and is directed directly to said spark plug.